Could someone advise about the length the new driveshaft key should be? The repro I received is 2 3/8 inches long but the original seemed to be about an inch longer or so. It's the second series driveshaft with the press on pinion late 28 to 31. It took a strong press to get it pressed off so it was tight. Is it better to use the original key, use the short key or find another supplier with more accurate parts?Thanks. Glynn.

Some of this is OP and some observation. The taper holds the gear to the shaft the key is there to line things up. Ether key should work, but if the the original is in good shape I would not have a problem using it.
Same with the rear axle tapers and keys.
The key sold today is the axle key for use in the pinion. If you check the parts book I am pretty certain that the pinion key carries a different parts number, which means it's a different key. If you want to make your own, it's just made out of 1/4" key stock.

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